The present invention relates to saw blades of the type used for cutting metal workpieces, such as band saw blades and hack saw blades. The invention relates more particularly to blades of this type having a novel form and arrangement of teeth which renders the blade smoother running and faster cutting and prolongs its operating life.
It has long been recognized that metal cutting blades of the conventional type which are characterized by being formed with teeth of uniform size and pitch throughout, tend to vibrate and be noisy in operation. In order to overcome these difficulties, and increase the wearing qualities of the blade, it has been proposed heretofore to form the saw with teeth of varying size and pitch as, for example, in accordance with the disclosure in U.S. Pat. No. 2,568,870 issued Sept. 25, 1951, wherein the teeth are arranged in groups which alternately increase progressively in gullet depth and pitch and then decrease progressively in gullet depth and pitch. While this arrangement does improve the functioning of the blade from a vibration and wear standpoint, it has the disadvantage of limiting the cutting speed of the blade. Normally, a decrease in speed can be avoided in accordance with the prior art by increasing the size and pitch of the teeth to the limits prescribed by the thickness of the material being cut and the desired surface finish. However, in a blade having teeth of varying size and pitch this limit applies to the size and pitch of the largest tooth, and since the remaining teeth are smaller in size and pitch, optimum citting speed cannot be attained and thus, the blade cuts more slowly.
Accordingly, it is an object of the invention to provide a saw blade of the type having teeth of variable length and pitch but without the disadvantage of poor cutting speed.
Another object is to improve saw blades of this type so as to obtain optimum operating characteristics such as reduced cutting noise and chatter, reduced vibration and smoother running, less heat generation, and longer blade life.
Other objects will be in part obvious and in part pointed out in more detail hereinafter.
A better understanding of the invention will be obtained from the following description and the accompanying drawing of an illustrative application of the invention.